One of the biggest steelmakers in Britain, second in size only to Tata, has said there is no guarantee that the industry will survive if the government fails to step up its response to the current crisis.

Sajid Javid has faced calls to stand down as the business secretary if a buyer is not found for the Port Talbot steelworks after admitting he was caught unaware by Tata’s planned withdrawal from the UK.

David Cameron defended Britain’s decision to reject higher EU tariffs on Chinese steel on Friday as the business secretary faced the anger of Port Talbot workers whose livelihoods have been undermined by cut-price imports.

Sajid Javid will travel to south Wales on Friday to promise steelworkers that the government will use all “ministerial, official and diplomatic levers” to help save their jobs, including actively seeking out buyers for Tata Steel’s British assets.

David Cameron has flown back to Britain for emergency talks with ministers over the financial crisis engulfing Tata Steel’s British operation – amid warnings that the firm has just weeks to secure a rescue deal on which up to 40,000 jobs could depend.